A polymorphic CD4 epitope related to increased susceptibility to Babesia bovis in Canchim calves

A small proportion of Zebu genetic background in crossbred calves may not be enough to improve resistance against natural bovine Babesia spp. infections

The main objective of cattle breeders in tropical and subtropical regions is to acquire animals with taurine-productive traits adapted to the broad weather range of these regions. However, one of the main challenges on using taurine genetics in these areas is the high susceptibility of these animals to tick-borne diseases. Consequently, the present study evaluated from 10 November 2021-19 April 2022, the over 13 assessments, the Babesia bovis and Babesia bigemina DNA loads and the IgG anti-B. bovis and anti-B. bigemina levels in Angus (n = 17, 100% Taurine) and Ultrablack (n = 14, ∼82% taurine and 18% Zebu) calves. Data were analyzed using a multivariate mixed model with repeated measures of the same animal including the fixed effects of evaluation, genetic group, sex, Babesia spp., and their interactions. The repeatability values were estimated from the (co)variances matrix and expressed for each species. The correlations between the DNA loads (CNlog) and IgG titers (S/P) values for the two species were also estimated using the same model. Regarding the specific IgG antibody titers for both Babesia spp., no significant differences were observed between the two genetic groups. However, for B. bovis and B. bigemina DNA loads, Ultrablack calves presented significantly higher values than Angus calves. Under the conditions evaluated in this study, our findings suggest that the low percentage of Zebu genetic in the Ultrablack breed was insufficient to improve resistance against babesiosis. Further studies must demonstrate if the low percentages of Zebu genetics in Taurine breeds can modify the susceptibility to babesiosis infections.

How long does the mRNA remains stable in untreated whole bovine blood?

BACKGROUND

High quality and quantity of messenger RNA (mRNA) are required for accuracy of gene expression studies and other RNA-based downstream applications. Since RNA is considered a labile macromolecular prone to degradation, which may result in falsely altered gene expression patterns, several commercial stabilizing reagents have been developed aiming to keep RNA stable for long period. However, for studies involving large number of experimental samples, the high costs related to these specific reagents may constitute a barrier.

METHODS AND RESULTS

In this context the present study was designed aiming to evaluate the stability of mRNA in whole bovine blood collected in EDTA tubes during storage at common fridge (4 °C). Whole blood samples were collected from six Holstein calves and submitted to RNA extraction in each different interval: immediately after blood sampling (< 2 h), at 1-day post-sampling (dps), 2 dps, 3 dps, 7 dps and 14dps intervals. RNA integrity and purity were evaluated, and RT-qPCR assays were run using seven different genes (B2M, ACTB, PPIA, GAPDH, YWHAZ, CD4 and IFN-γ) aiming to evaluate the presence of altered gene transcription during storage. All extracted RNA samples presented high purity, while optimal integrity and unaltered gene expression were observed in whole experimental group up to 3 days of storage.

CONCLUSION

Bovine blood RNA remained stable in K3EDTA tubes for 3 days stored at common fridge and can be successfully and accurately used for gene expression studies.